DE2160118A1 - Process for the production of biaxially oriented polyamide film - Google Patents

Description

"Process for the production of biaxially oriented polyamide film"

Priority: December 4, 1970 - Japan - No. 107 843/1970 Dec. 04, 1970 - Japan No. 107 844/1970

The present invention relates to a process for the production of biaxially oriented polyamide film based on a polyamide with m-xylylene groups in the whey cooling structure, the stretched Film has excellent mechanical and physical properties and in particular shows a high gas impermeability.

It is known per se, films with high utility value and in particular to produce improved mechanical and physical properties by using a non-oriented thermoplastic The film stretches in two mutually perpendicular directions. For carrying out such biaxial stretching measures A wide variety of procedures and methods have been recommended, which are essentially divided into two groups, namely 3n a simultaneous hedge in the longitudinal and transverse direction and in a successive stretching in the longitudinal and transverse directions. However, if you have such a simultaneous stretching measure on foils

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made of an aliphatic polyamide such as polycaprolactam., a stretched film with poor shrinkage behavior is obtained in this way and insufficient dimensional stability. That gradually or successive biaxial stretching, on the other hand, can only be carried out with difficulty on an industrial scale.

Surprisingly, it has now been found that the above mentioned deficiency can be eliminated and that a polyamide film without the occurrence of unevenness is good can be stretched if the stretching process is carried out within a temperature range which is carried out in a special way with regard to the moisture content of the unstretched film and the stretching speed is regulated. In this way, stretched films with very satisfactory shrinkage behavior and good dimensional stability can be produced produce.

The inventive method for producing biaxial stretched polyamide film is characterized in that an unstretched polyamide film which contains at least 70 mole percent of repeating monomer units derived containing m-xylylenediamine or a maximum of J> 0 mole percent p-xylylenediamine mixture of m- and derive p-xylylenediamine and an aliphatic U , O-dicarboxylic acid with 6 to 10 carbon atoms in the molecule, stretching either simultaneously or successively in the longitudinal and transverse directions within a temperature range which, with simultaneous biaxial stretching according to the inequality

-1OW + 120 + 12log -) T \ -6W + 80 (l)

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and in the case of biaxial stretching in stages or in succession according to the inequality

-1OW + 130 + Tiog- ^ Q-> T I -6W + 80 (2)

determined, where W is the moisture content of the unstretched film in percent by weight, 6 is the percentage stretching speed (Percent / minute) means and T is the stretching temperature in C.

In the method according to the invention, preferably un-

sicfr

Stretched polyamide films are used in which / the repetitive Monomer units of: mixtures of m- and p-xylylenediamine derive which no more than 15 mole percent p-xylylenediamine contain. In addition, it is essential in the context of the invention that the repeating monomer units are at least 70 mole percent from the relevant xylene diamines and an aliphatic t /., il-dicarboxylic acid with 6 to 10 carbon atoms in the molecule exist.

It is very useful if the film to be stretched consists of a polyamide with a relative viscosity (concentration: 1 g of polyamide in 100 ml of solution, solvent: 96 percent strength by weight sulfuric acid, Measuring temperature: 25 ° C.) from 2.0 to 4.0 and in particular from 2.2 to 3.0.

The polyamide in question can, for example, be a homopolymer be, such as poly-m-xylylene adipamide, poly-m-xylylene sebacic amide and Poly-m-xylylene suberinate. They also come as basic substances

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copolymers are also possible, for example copolymers made of m-xylylene and p-xylylene adipamide, copolymers from m-xylylene- and p-xylylene-pimelinamide, copolymers from m-xylylene and p-xylylene sebacinamide and copolymers m-xylylene and p-xylylene azelaine amide.

There are also copolymers of the monomers mentioned above Components and aliphatic amines such as hexamethylenediamine, alicyclic diamines such as piperazine, aromatic diamines, such as p-bis (2-aminoethyl) benzene, aromatic dicarboxylic acids such as terephthalic acid, lactams such as β-caprolactarn, -Ω - aminocarboxylic acids, such as 7-aminoheptanoic acid and / or aromatic aminocarboxylic acids, such as p-aminomethylbenzoic acid, into consideration.

In addition, the basic substance for the films can also contain other polymer components, for example polycaproarnide, polyhexamethylene adipamide, Polyhexamethylene sebacinamide, polyundecanamide, polyethylene terephthalate, polyethylene and / or polypropylene. P It is also possible for additives to be incorporated into the film, such as antistatic agents, lubricants, antiblocking agents, stabilizers, dyes and / or pigments.

The unstretched film is in the practically unoriented State and may have been obtained by a conventional film production process, for example by a process in which the polyamide melt is processed into a film, as in the extrusion process using slot dies or after the blown film process. There are also wet casting processes and

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BATHROOM OBlGlNAL

Dry casting process into consideration. When making the unstretched Film in the extrusion process with a slot die is, for example, the polyamide used as the starting material, to which additives may have been incorporated, heated to a temperature above the melting point, and the polyamide melt is then pressed out through the slot die, and the film thus formed on a roller or in a liquid bath maintained at a temperature of from 0 to 70 ° C cooled to a temperature below the freezing temperature rature lies. If the temperature of the cooling roller or the liquid cooling bath is above the freezing temperature during such a procedure is, then the film in question is not plane-parallel and shows flow seams, so that a subsequent stretching is only can be carried out with great difficulty.

The freezing temperature can be determined in a known manner by means of a dilatometer from the temperature dependence of the determine the specific volume. . .

An unstretched film produced in this way can then according to the invention either simultaneously or biaxially in stages within the temperature ranges provided according to the invention be stretched.

In the case of the in two perpendicular directions .simultaneously stretching must take place at the stretching temperature in the area which is determined by the inequality (1). If the biaxial stretching is carried out in stages, the stretching temperature must

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rature must be kept within the range determined by the Inequality (2) is determined.

The moisture content W of the unstretched films can be determined in a manner known per se, for example using the weight method or according to the Karl Fischer method.

The percentage stretching speed (o) is determined from the Stretching ratio per unit of time and can be calculated using the following equation:

percentage Reckge- _ ioo length after stretching / R ^ec kzeit in speed ~ length before stretching 'minutes (/ ml)

When the process according to the invention is carried out in practice, the percentage stretching speed is the simultaneous biaxial stretching generally 500 to 50,000 percent / minute and preferably 1,000 to 10,000 percent / minute. In the gradual carried out biaxial stretching, the percentage stretching speed is generally in the range from about 500 to. 500,000 percent / minute for longitudinal stretching and from about 500 to 50,000 percent / minute for transverse stretching. Preferably, the stretching in the longitudinal direction is carried out at a percentage stretching speed of about 1,000 to 100,000 percent / minute and stretching in the transverse direction at a percentage stretching rate of about 1,000 to 50,000 percent / minute carried out.

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The stretching ratio in each stretching direction is usually in the range of 2 to 6, and preferably 2.5 to 4.5. Here can the stretching ratio in both stretching directions can be identical or different from one another.

The percentage stretching speed depends on both

also at
According to the biaxial stretching that takes place in succession or in stages, it depends on the most varied of influencing variables, for example the thickness and the physical properties of the unstretched film, the stretching machine used and also on purely economic considerations. If the stretching ratios in the longitudinal and transverse directions are identical, the corresponding percentage stretching speeds in these two directions are also the same. If, on the other hand, the stretching ratios are different in the two stretching directions, the percentage stretching speeds can also be different. In the last-mentioned case

the ratio of the percentage stretching speed in the longitudinal direction to that in the transverse direction is usually in the range from 0.5: 1 to 2: 1. Smaller or larger proportions of the percentage stretching speeds generally offer no advantages because this reduces the unevenness in the Stretching is increased or the film even breaks.

The moisture content of the unstretched film depends quite significantly depending on the environmental conditions under which the film was produced can, however, be regulated in an appropriate manner will. Typically, the moisture content of the unstretched film is between about 0.1 and 5 percent by weight, with a

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- δ - ■ ■

Range of 0.3 to 3 weight percent is preferred.

When the simultaneous or stepwise biaxial stretching at a Temperature is taken which is in a range defined by the above inequalities (l) and (2), then a very uniformly stretched film is obtained. On the other hand, if the stretching is carried out at a lower temperature, so a much higher force is required for the stretching process, and- then very often occurs in the initial stages of the stretching process a break in the foils. On the other hand, when the stretching process is carried out at a higher temperature than that by the above Inequalities is determined, then occur at stretching ratios of about 2.7 to 3/0 constrictions, so that the The film has an uneven thickness and then a film break occurs in the final stage of the stretching process.

The relationships described above are explained in more detail with reference to FIGS. 1 and 2. Figure 1 refers to the simultaneous biaxial stretching and FIG. 2 shows the biaxial stretching carried out in stages. In the graphs FIGS. 1 and 2 show the dependence of the stretching temperature on the moisture content of the films concerned. The straight lines A and B indicate the lower and the upper for a percentage stretching speed of 1000 percent / minute Limit for the stretching temperature again, while the straight line C is the upper limit of the stretching temperature for a percentage stretching speed of 30,000 percent / minute. Suitable stretching equipment are therefore in the hatched areas between the

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Straight lines A and B or between straight lines B and C, depending on the one used percentage stretching speed.

The simultaneous stretching can take place in a manner known per se, for example using a tenter frame or by means of the blowing method.

In the case of the stepwise biaxial stretching, you can use two or more Roller systems work., Which one behind the other in the pull-off direction of the film are arranged and have different rotational speeds. When trying to slide out an aliphatic To stretch polyamide, such as polycapronamide or polyhexamethylene adipiriamide, in one direction using conventional measures, then constrictions usually occur and a uniform stretching becomes very difficult, unless you are working with one very much high stretching ratio. According to the present invention, however, uniform stretching can be carried out without difficulty. For stretching of the film in the transverse direction, both film edges are held by means of clamping devices and the stretching is carried out on a heated one Tenter frame carried out. The sequence of stretching processes in the longitudinal direction, and transverse direction can be chosen arbitrarily, i.e. you can first in the longitudinal direction or first in the transverse direction stretch.

Regardless of whether the biaxial stretching is carried out successively or simultaneously, the film stretched according to the invention shows a lot good properties. If desired, however, you can still have one subsequent thermal treatment, whereby the treatment

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- ίο -

temperature is in a range that is 5 ° C higher than the stretching temperature used and, at most, the melting temperature of the stretched film. The duration of the aftertreatment is no more than 5 minutes and is preferably in the range of about 15 to 60 seconds. During this aftertreatment, the film can be kept in the stretched or relaxed state will. Such a thermal aftertreatment increases the degree of crystallinity of the film and during the stretching process Any internal stresses that arise are eliminated, thereby improving the overall mechanical properties and the durability of the Foil can be increased.

A film produced in this way shows an excellent crystal! - degree of nature and well-balanced properties with regard to the degree of orientation. The degree of orientation expressed as a planar orientation index is, for example, 0.025 or more, and the ' The difference in the degree of orientation is, for example, 0.045 or less. In addition, the stretched films produced in this way show excellent light transmittance, and the haze value is generally 3 * 0 or less.

It was previously assumed that when a polyamide film is stretched in one direction, a molecular orientation in the stretching direction, with simultaneous formation of hydrogen bonds takes place, so that a subsequent stretching in a transverse direction perpendicular thereto presents great difficulties. According to the invention Surprisingly, however, the biaxial stretching process for polyamide films can be carried out extremely easily.

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- li -

Since the range of stretching conditions is very broad according to the invention, and the stretching can be carried out within a wide range of the stretching ratio, films of any desired physical properties can be generated.

The biaxially stretched films obtained according to the invention show excellent tensile strength, a high yield point, a Young's high modulus, good heat stability, good dimensional stability, high light transmittance and excellent Impermeability to gases, ^ i ι-. · Differentiate thereby advantageous from known biaxially stretched films made of aliphatic linear polyamides ,, such as polycapronamide and Polyhexame'thylenadipinamid, and are therefore particularly suitable as packaging material for food, fibers and Machine parts and for use in tape form or as starting material for photographic films. The high gas impermeability results, for example, from the value of the permeation coefficient

-13 / 2

ten compared to oxygen of 5 x 10 ml.cm/cm. se'c.cmHg in comparison to biaxially stretched films made of polyethylene terephthalate with a corresponding permeation coefficient of 3 χ 10 and of films made of polycapronamide with a permeation coefficient from 2 χ 10 ".

Films stretched according to the present invention generally show the following mechanical and physical parameters: tensile strength

14 kg / mm or more; Elongation at break 30 to 150 percent and occasionally 50 to 100 percent; Yield strength 7 kg / mm or flour ¹ , irrespective of

also borrowed 10 kg / mm or more .; Elongation at maximum force 2 to 6

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Percent and occasionally 3 to 5 percent.

The following test methods are used in the examples below used for characterizing the mechanical and physical properties of the stretched films according to the invention.

(1) Relative viscosity:

Concentration 1 g polyamide per 100 ml solution, solvent 96 percent by weight Sulfuric acid; Measuring temperature 25 ° C.

(2) The tear strength and elongation at break are determined in accordance with ASTM standard D 882.

(5) The yield point and the elongation at maximum force will be determined according to ASTM standard D 882.

(4) Turbidity value: -

This parameter is determined using an opacimeter (manufacturer: Toyo Seiki K.K.) and calculated according to the following equation.

AWAY
Turbidity value = - - χ 100

where A is the total amount of light transmitted and the difference A-B means the amount of scattered light.

(5) Shrinkage:

A sample 65 rm long and 10 mm wide is left on which two points are marked 50 mm apart, for 1 hour in

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stand in a drying oven at a temperature of 130 ° C. the Change in length AL between the marked points is then send and the shrinkage is calculated according to the following equation:

Shrinkage = χ 100

50

(6) Permeation coefficient for oxygen:

This coefficient is measured using a commercially available measuring apparatus (manufacturer: "" Rika Seiki Ko _& yosha) at JO ⁰ C under the conditions of ASTM standard D 1454-58.

(7) Planar Orientation Index and Difference in Degree of Order: Using a refractometer, the refractive indices a polishing sample in the longitudinal direction (χ), in the transverse direction (y) and measured in the direction of the pile thickness (z) and the two parameters are calculated from this according to the following equations:

Planar orientation index = ■ · ζ

Difference in degree of order = χ - y

For example

A mixed polymer of m-xylylene and p-xylylene adipamide (MoI ratio m-xylylene: p-xylylene = 99: 1; relative viscosity: 2.21) is melted at 260 ° C and through a slot die extruded onto a chill roll, whereby an un-

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stretched film with a thickness of 200 μ is obtained. Samples of this film are allowed to condition under a wide variety of humidity conditions. The unstretched films with different moisture content obtained in this way are then subjected to a simultaneous biaxial stretching process with identical stretching in the longitudinal and transverse directions on a tenter frame, the percentage stretching speed and the stretching temperature being varied.

The results obtained are summarized in Table I below.

In the "Result" column of this table have the specified there Signs or abbreviations have the following meaning:

0 = satisfactory behavior when stretching; BE = break at the beginning of the stretching process; BL = break at a later stage of the stretching process;

IT = stretching temperature within the range according to the invention; CT = stretching temperature outside the range according to the invention.

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- 15 Table I.

EJLien-
sample
No. ? euchtig-
Kieitsge-
stop (J6) Horizontal bar
ver
ratio Percent
tuale Re
swiftly
speed Temperature
cure
ig- ( ⁰ C) Result
nis tempera
turbe
rich 1 0 ^ 20 4 ^ 0 30,000 85 0 IT 2 0.20 30,000 77 BE OT 3 0.20 .1 000 77 BL CT 4th 0.40 4.0 30,000 . 98 0 IT 5 0.40 4.0 30,000 90 0 IT 6th 0.40 4.0- 5,000 90 0 IT 7th 0.40 3.5 1,000 90 0 IT 8th 1.84 3.5 10,000 90 0 IT 9 1.84 4; 0 30,000 70 0 IT 10 1.84 3; 0 5,000 70 0 IT 11 1.84 3.0 5,000 66 BE CT 12th 2.96 3; 5 30,000 55 BE CT ! 3 2.96 3.0 5,000 55. BE CT 14th 4.28 4.0 30,000 60 0 IT 15th 4; 28 3.5 1,000 60 0 . IT 16 4.28 2.0 5,000 40 BL . CT 17th 6.60 3.5 30,000 45 0 IT 18th 6.60 2.0 30,000 35 BL CT 19th 6.60 3.5 30,000 35 BE CT 20th 0.20 3.5 1,000 120 BL CT 21st 0.20 3; 0 1,000 125 BL CT 22nd 0.20 4.0 30,000 120 0 IT 23 0.20 4.0 5,000 120 0 IT 24 0.20 4.0 10,000 110 0 IT 25th 1.84 3.5 1,000 100 0 IT 26th 2.96 3.5 1,000 93 BL CT 27 4.28 3.5 1,000 74 0 IT 28 6.60 3.5 1,000 55 BL CT 29 6.60 3.0 10,000 55 0 IT 30th 6.60 3.5 1,000 50 0 IT 51 0.20. 3.5 5,000 130 BL CT 32 1.84 3/5 5,000 ■ 110 BL CT 33 2.96 3.5 5,000 95 0 IT 34 4.28 3.5 5,000 90 BL CT

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- 16.- Continuation of Table I

Eölien
sample
No. · Damp
keitsge
stop {%) Horizontal bar
ver
ratio Percent
tuale Rc
swift
speed Ternpe-
ick- nature
lie ( ⁰ C) Result
nis tempera
turbe
rich 35 6.60 3.5 5,000 60 IT 36 6.60 3.5 5,000 65 BL CT 37 6.60 4.0 30,000 65 IT 38 0.20 3.5 10,000 135 BL CT 39 0.20 3.5 10,000 128 Sf IT 40 1.84 3.5 10,000 110 $ it ■ 41 2.96 3.5 10,000 105 BL CT ' 42 4.28 3.5 10,000 85 Sf IT 43 6.60 3.5 10,000 75 BL CT 44 6.60 3.5 10,000 65 Sf IT 45 " 0.20 4.0 30,000 140 BL CT 46 0 _; 20th 3.0 10,000 140 BL CT 47 0.20 3.75 30,000 135 Sf IT 48 1.84 3.5 30,000 125 BL CT 49 2.96 3.5 30,000 105 0 IT 50 4.28 3.5 30,000 120 BL CT 51 4.28 3.5 30,000 100 BL CT 52 4 _; 28. 3.5 30,000 90 0 IT. 53 6.60 3.5 30,000 110 BL CT 54 6.60 3.0 30,000 80. BL CT 55 6.60 3.5 30,000 65 0. IT

Example 2

According to Example 1 obtained biaxially stretched film samples Nos. 4, 7, 8, and 55 seconds J50 are heated to a temperature of 200 ⁰ C for subsequently.

The physical properties of the thermally rebellious one! 1en Films are summarized in Table II below.

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Table II

Foil sample no. '4: Querrich
tion 7th Along
direction Querrich
tion 8th Along
direction Querrich
tion 55 Querrich
tion Tear resistance
(kg / mm ² ) Along
direction 29.8 18.0 20.1 18.4 19.7 Along
direction 14.4 Elongation at break {%)
'. 23.4 54 102 100 104 117 13.4 UO Stretch limit
(kg / mm ^) 59 , 13.8 13.5 13.7 ii, 3 I. 11.8 108 11.1 Elongation at maximum
force {%) 13.5 *. 3.1 3.6 3.2 4.0 4.2 11.6 3.5 Shrinkage ($) 3.5 2.1 ■ 1.3 1.4 : 1.1 1.1 3.7 1.0 Permeation coefficient
cient for oxygen 1.9 2.9k 10 "P 4.5 χ ΙΟ ^'15
t ι ■ ^! 4.6 χ OK " ¹⁵
I. 0.9 3.4 χ io ~ ¹⁵ Planar ^! Orientations
index ■: -! ! ■
; 0.040 i
0.036 ■ 1 :
1
0.036 0.024 Difference in ord
degree of efficiency -0.011 -O, .OO7 -0.011 -0.003 Turbidity value {%) ; i, 8
i 1.2 1.3 2.0

Example J

The unstretched films produced according to Example 1 are conditioned under a wide variety of moisture conditions and then subjected to a simultaneous stretching process, wherein however, the stretching ratios in the longitudinal direction and in the transverse direction are different. The results thereby obtained are as follows summarized in Table III.

Table III

Foils
sample
No. Damp
activity
salary
(*) Stretching ratio Cross
rich
tion Percentage horizontal bar
speed
($ / Min.) Cross
rich
tion tempera
door
Cc) Result
nis 56
57
58
59 0.40
1.84
0.20
4.28 Along
rich
tion 2.8
3.6 ■
3.0
3.6 Along
rich
tion 5000
6000
7500
1200 90
70
110
74 0
0
0
0 4.2
3.0
4.0
3.0 ' 7500
5000
10,000
1000

Example 4

The unstretched films obtained according to Example 1 are conditioned and under the most varied of moisture conditions then subjected to a stepwise biaxial stretching process, wherein Stretching is carried out first in the longitudinal and then in the transverse direction, with the exception of film samples No. 64 and No. 78, in which initially in Was stretched transversely and then lengthways. ' There are the most varied percentage stretching speeds and the most varied Stretching temperatures applied. The results obtained are summarized in Table IV below.

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Damp
.tig-
ability
salary
(*) Tabel : First stretching treatment Percent u
ale horizontal
speed
age
(g / toin.) Tempe
rature
( ⁰ C) Result
nis CV Second stretching treatment ¹ tempe
rature
( ⁰ C) Result
nis - 19 - Foil
ιλτάΤλο 0.20 Horizontal bar
ver
holds-
nis 30,000 85 0 Percent u
ale horizontal bar
speed
age
(# / Min.) 90 temperature No. 0.20 4.0 30,000 '75 BE Horizontal bar
ver
holds-
nis 5,000 - - area. 61 0.20 3.5 5,000 75 BE 3.0 - - - IT 62 0.20 2.0 , 5,000 90 0 - 105 0 CT 63 0.20 3.5 10,000 115 ύ - 30,000 120 0 CT 64 0.20 4; 0 10,000 115 ύ 4.0 1,000 130 BL IT G 5 0.20 4.0 1,000 130 BL 3.5 1,000 - - IT 66 0.20 4.0 5,000 130 : ύ 3.5 - 135 0 CT 67 0.20 4.0 10,000 130 0 ■ r 30,000 140 BL CT 68 0.40 4 ₇ O 30,000 95 ■ · 0 3.0 30,000 100 0 IT 69 0.80 3.5 30,000 85. ■ 0 3.0 5,000 100 0 CT. 70 1.84 3.75 30,000 70. 0 3.5 2,000 80 0 . _IT . 71. 1.84 3.5 10,000 100 0 3.5 5,000 110 0 IT 72 1.84 4.0 10,000 100 . 0 4.0 1,000 118 ' BL ■ _IT . 73 1.84 4 _r 0 10,000 100 : 0 3.0 1,000 118 BL IT 74 1.84 4.0 10,000 100 0 3.0 5,000 118. CT 75 2.96 4.0 1,000 65 0 3.0: 10,000 60 BE CT ... 76 2.96 2.5 5,000 80 0 3.0 5,000 90 0 IT 77 3.5 ' 2.0 30,000 CT 78 4.0 IT

CD CO 00

Table IV continued Foil Damp First stretching trade Percent u
ale horizontal
gsschwin-
age
(# / Min.) Tempe
rature
. ( ⁰ C) iOrgeb-
nis. Second stretching treatment Horizontal
ver
holds-
nis frozentu
lle bar
jescirwin-
activity
f ^ / min. l t 30,000 Tempe
rature
( ⁰ C) iCrgeo-
nis - 20 - orobe
*No. tlg-
ability
salary
. (#) Horizontal bar
ver
holds-
nis 1,000 103 " BL - 30,000 - - temperature 79 2.96 5,000 103 0 3.5 1,000 109 0 area 80 2.96 3.5 5,000 103 0 3.5 30,000 115 BL CT 81 2.96 3.5 30,000 109 9 3.0 - 115 ' BL IT P ' 2.96 4.0 30,000 109 0 . ⁵ > ⁵ 1,000 115 BL CT 85 2.96 4.0 30,000 50 BE 1,000 - - CT 64 4; 28 2.0 30,000 60 0 4.0 5,000 75 0 CT 85 4; 28 3.0 1,000 85 0 3.0 30,000 90 BL CT 86 4.28 3.5 1,000 85 0 3.0 10,000 90 0 IT '■ 87 4; 28 3.5 1,000 85 0 3.0 30,000 95 0 CT 83 4.28 3.5 1,000 85 0 3.0 - 95 Bl IT 69 4.28 3.5 5,000 90 0 3.5 _ 100 BL IT 90 4.28 3.5 30,000 100 BL - i 000 - - CT 91 4.28 3.5 1,000 35 BE - 30,000. - -, CT OO 6.60 2.0 1000 45 0 3; 0 30,000 55 9 CT 93 6.60 4.0. 10,000 70 0 2 _T 7 73 0 CT 94 6.60 3.5 10,000 70 0 2.7 83 BL IT ος 6.60 3.5 IT CT

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Example 5

No. 70 and The biaxially stretched film samples obtained according to Example 4 /

30 seconds heated at 200 ⁰ C and 20 seconds at 230 ° C. The physical properties of the film samples thermally aftertreated in this way are summarized in Table V below.

Table V

Foil sample no. 70 Querrich
tion f 3,1 χ ίο " ¹ - ⁵ 71 Longitudinal
tion Querrich
tion Tear resistance
(kg / mm ² ) Longitudinal
tion 28.1 0.039 23.6 25.0 Elongation at break (%) 25.0 50 -0.031 67 38 Stretch limit
(kg / mm ² ) 102 13.6 1.0 11.0 11.7 Elongation at maximum
force (#) 13.7 3.4 3.6 3.1 Shrinkage {%) 2.9 2.1 1.6 2.0 Permeation coefficient
cient for oxygen o, 9 2.6 χ 10 " ^{i: 5} Planar orientation
ration index 0.040 Difference in ord
degree of efficiency -0.03.4 Turbidity value {%) 1.2

209824/1091

Claims (8)

- 23 claims 1. Process for the production of biaxially stretched polyamide film, characterized in that an unstretched Polyamide film, which is at least 70 mole percent from itself repeating monomer units that differ from m-xylyiene diamine or one containing at most 30 mole percent p-xylylene diamine Mixture of m- and p-xylylenediamine and an aliphatic one d-i-fl-dicarboxylic acid with 6 to 10 carbon atoms in the molecule derive, is stretched either simultaneously or successively in the longitudinal and transverse direction within a temperature range, which with simultaneous biaxial stretching according to the inequality -1OW + 120 + 12 ^ og— £ y T y -6W + 80 (l) 1000 and in the case of biaxial stretching in stages or in succession according to the inequality -1OW +130 + 7 iog Ö \ _T > -6W + 80 (2) 1000 = determined, where W is the moisture content of the unstretched film in percent by weight, S is the percentage stretching speed (^ / minute) and T is the stretching temperature in ⁰ C. 2. The method according to claim 1, characterized in that the film to be stretched made of a polyamide with a relative viscose (Concentration: 1 g of polyamide in 100 ml of solution, solvent 9; 5%, .3% strength sulfuric acid; measuring temperature:? 5 ° C) of 2.0 to 4.0. 20982Λ / 1091 3. The method according to claim 1 or 2, characterized in that that the biaxial stretching is carried out simultaneously and with a percentage stretching speed of 500 to 50,000 percent / Minute. 4. The method according to claim 1 or 2, characterized in that that the biaxial stretching is carried out in stages and with a percentage stretching speed of 500 to 500,000 percent / Minute in the longitudinal direction and at a percentage stretching speed of 500 to 50,000 percent / minute in the transverse direction. 5. The method according to claim 1 to 4, characterized in that that the stretching takes place both in the longitudinal direction and in the transverse direction with a stretching ratio of 2 to 6. 6. The method according to claim 1 to 5 *, characterized in that that the unstretched film has a moisture content of -0.1 to 5 percent by weight. 7. The method according to claim 1 to 6, characterized in that that the stretched film undergoes a thermal aftertreatment is subjected to a temperature which is at least about 5 C above the stretching temperature and just below the melting temperature the stretched film lies. 8. The method according to claim 7 # characterized in that the thermal aftertreatment is no longer carried out for> 5 minutes will. 209824/1091 bad ORiQ Blank page